The insecticide can damage people's kidneys, liver and thyroid glands if eaten in large quantities. However, food standards agencies are playing down the risks for anyone who has already eaten the tainted eggs.

Which countries are affected?

Farms were shut down in the Netherlands, Belgium, Germany and France after authorities confirmed that fipronil had been used, European Commission spokesman Daniel Rosario said on Friday.

The EU countries that have received the eggs are the UK, Sweden, Austria, Ireland, Italy, Luxembourg, Poland, Romania, Slovenia, Slovakia and Denmark. Non-EU Switzerland is also affected.